Interferon-induced enzyme activities such as the oligo(2' 5') adenylate synthetase, the 67K dalton protein kinase and oligo(2' 5') A phosphodiesterase are investigated with a goal of understanding their role in the action of interferon, the induction of interferon by double-stranded RNA and, perhaps, control of cell growth and differentiation. Analogs of the mediator of interferon action, 2-5A, are synthesized in order to define the relationship between oligonucleotide structure and binding to and activation of the 2-5A dependent endonuclease with eventual goal of designing useful chemotherapeutic agents based on this system.